People with type 2 diabetes more at risk of cancer mortality, study shows

Individuals living with type 2 diabetes are nearly 20 per cent more likely to die from cancer compared to those without, latest research reveals.

The study has also found that people living with type 2 diabetes are nine per cent more at risk of being diagnosed with breast cancer.

Funded by Hope Against Cancer, the research has identified that having type 2 diabetes also increases your chances of developing colorectal cancer by 2.4 per cent.

Accumulating epidemiological evidence has shown a higher risk of incidence and mortality for some types of cancer in individuals with type 2 diabetes, with prolonged exposure to the effects of increased blood sugar and insulin levels, insulin resistance and chronic inflammation being the potential underlying biological mechanisms.

Robust evidence indicates that there is a causal relationship between type 2 diabetes and pancreatic, liver and endometrial cancer.

While previous studies have extensively investigated inequalities in cardiovascular outcomes among people with type 2 diabetes, less is known about whether such inequalities exist in cancer mortality rates.

In this study, the authors used a cohort of individuals aged 35 years or over who had newly diagnosed type 2 diabetes in the Clinical Practice Research Datalink, a UK general practice database, over a 20-year period between 1 January 1998 and 30 November 2018.

They analysed trends in all-cancer and cancer-specific mortality rates by age, gender, ethnicity, socioeconomic status, obesity and smoking status.

They also estimated standardised mortality ratios comparing mortality rates in people with type 2 diabetes with the general population.

The study included 137,804 individuals with newly diagnosed type 2 diabetes with median follow-up of 8.4 years. The authors found all-cause mortality rates decreased at all ages between 1998 and 2018; cancer (all cancers combined except non-melanoma skin cancer) mortality rates also decreased for 55-year-olds (by 1.4% per year) and 65-year-olds (by 0.2% per year) but increased for 75-year-olds (by 1.2% per year) and 85-year-olds (by 1.6% per year).

Dr Suping Ling leaded the study. The authors said: “From this perspective, our results suggest that it may be helpful to extend breast cancer screening to young women with type 2 diabetes.

“However, given the high cost and potentially longer exposure to screening procedures, cost-effectiveness analyses are required to define the appropriate time window and identify subgroups who may benefit more.”

They add that there are currently trials investigating extending the existing breast cancer screening window from 50-70 years to 47-73 years in the general population; in addition, women with a family history of breast cancer or specific gene mutations are offered screenings from a younger age, but no current guidelines specifically consider the increased risk of breast cancer in women with diabetes.

The authors noted: “The prevention of cardiovascular disease has been, and is still considered, a priority in people with diabetes.

“Our results challenge this view by showing that cancer may have overtaken cardiovascular disease as a leading cause of death in people with type 2 diabetes.”

They added: “Cancer prevention strategies therefore deserve at least a similar level of attention as cardiovascular disease prevention, particularly in older people and for some cancers such as liver, colorectal and pancreatic cancer.

“Tailored interventions should also be considered for smokers, who had higher and steadily increasing cancer mortality rates. For people with type 2 diabetes, early cancer detection through changes to existing screening programmes, or more in-depth investigations for suspected/non-specific cancer symptoms, may reduce the number of avoidable cancer deaths.”

The authors conclude: “In conclusion, our findings underline the growing cancer burden in people with type 2 diabetes, particularly in older individuals, and highlight the need to prioritise cancer prevention, research and early detection and management in this population, especially for colorectal, pancreatic, liver and endometrial cancer, whose mortality rates were substantially higher in individuals with type 2 diabetes than in the general population.”

Dr Lucy Chambers, Head of Research Communications at Diabetes UK, said: “If you’re living with type 2 diabetes, over time, high blood glucose, blood pressure and blood fat levels can cause serious long-term damage to the body, including to the eyes, heart, nerves and kidneys. Type 2 diabetes is also linked to increased risk of developing certain types of cancer, and both conditions can have common risk factors.

“This research indicates that while people with type 2 diabetes in the UK tend to be living longer, deaths from some type of cancers appear to be increasing, particularly in older people with type 2 diabetes. These findings highlight the need for further research into cancer causes and prevention in this population.”

She added: “For more information on living with diabetes and cancer, visit https://www.diabetes.org.uk/diabetes-the-basics/related-conditions/diabetes-and-cancer.”

The study was published in the journal Diabetologia.

Photo by Angiola Harry on Unsplash